The present invention relates to a method for operating an image sensing device and an image sensing apparatus adopting the method and, more particularly, to an operation method for driving an image sensing device comprising a plurality of pixels arranged in two dimension, and an image sensing apparatus having the image sensing device and an image sensing method which adopt the operation method.
FIG. 12 shows a brief configuration of a conventional interline-type solid-state image sensing device. In FIG. 12, reference numeral 101 denotes pixels, each including a photoelectric converter, for storing charges; 102p, vertical transfer charge-coupled devices (VCCDs), each including a plurality of CCDs operated by four different operation pulses, which are provided along vertical lines (i.e., columns) of the pixels 101; and 103p, a horizontal transfer CCD (HCCD), electrically connected to the VCCDs 102p, having a plurality of CCDs operated by two different operation pulses. The VCCDs 102p and the HCCD 103p are shielded from light. Further, reference numeral 104 denotes a charge detector; 105, an output terminal for outputting signals; and 106p, 107p, 108p and 109p, input terminals of the operation pulses to the VCCDs 102p, and respective operation pulses are supplied to the VCCDs 102p. Reference numerals 114p and 115p denote input terminals of operation pulses to the HCCD 103p, and respective operation pulses are provided to the HCCD 103p.
Next, an operation of the image sensing device having the above configuration is explained.
Charges obtained by photoelectric conversion and stored in the pixels 101 are transferred to the VCCDs 102p, and sequentially transferred toward the HCCD 103p in accordance with the four operation pulses .phi.V1p, .phi.V2p, .phi.V3p and .phi.V4P. The HCCD 103p transfers charges of one horizontal line (i.e., row) transferred from the VCCDs 102p to the charge detector 104 in accordance with the two operation pulses .phi.H1p and .phi.H2p. The transferred charges are converted into voltage signals by the charge detector 104, then outputted from the output terminal 105.
Further, the image signals outputted from the image sensing device are transformed into signals of a predetermined format by applying predetermined signal processes in not-shown circuits, then recorded on a variety of recording media, displayed on a display device, or outputted to outside.
With the advance of technology, the number of pixels used in an image sensing device has increased, and now it is not a rare case that the number of pixels used in an image sensing device is greater than the number of pixels used in an output device. The above situation often happens when displaying a sensed image on a liquid crystal display (LCD), for example, since the number of pixels used in an LCD is much lower than that of an image sensing device in many cases (e.g., about 240 rows). When outputting an image sensed by a conventional image sensing device to such an output device, signals of all the pixels of the image sensing device have to be read out, stored in a recording medium, such as a memory, then thinned down to the necessary number of rows of signals for the output device, and outputted. Therefore, a memory and a processing circuit for thinning signals are necessary, which increases complexities of circuits as well as manufacturing cost.
Furthermore, as the number of pixels used in the image sensing device increases, it takes longer to read signals of all the pixels. As a result, the number of images obtained in one second decreases, thereby a smooth moving image can not be obtained. The above problem can be solved by operating the image sensing device at higher speed, however, it becomes necessary to improve performance of semi-conductor in that case, which also causes an increase in manufacturing cost.